Determination of the specific interaction between Cap and anti-Cap VHHs by indirect ELISA.

<p>A, The plate was coated with PCV2 viral lysis (10^−6.4 TCID₅₀, 1∶800 dilution). B, The plate was coated with purified Cap protein (0.5 µg/ml). The positive serum in A and B was the anti-Cap serum taken from a pig. Negative 1 and 2 in A represent the wells coated with BSA (negative control 1) or the lysis of PCV2 uninfected FPRC cells (negative control 2), respectively. Negative 1 and in B represent the wells coated with BSA (negative control 1) and 0.5 µg/ml purified MBP tag (negative control 2). The absorbance at 450 nm indicated the binding activity between selected VHHs and Cap. Data is plotted as the average of 3 wells, with error bars representing the standard deviation.